Millions of middle-aged and elderly people already take a low-dose aspirin to lower their risk of heart attack or stroke. But could their daily preventive be staving off cancer too? New research published Dec. 7 in The Lancet suggests that it does.

Peter Rothwell, a neurologist at Oxford University, oversaw the analysis of eight previous randomized controlled trials involving 25,570 people, in which some people were given 75 mg to 100 mg of aspirin per day (baby aspirin contains 81 mg) and others were given a placebo. Overall, patients who took aspirin regularly for several years were 20% less likely to die of solid tumor cancers, such as cancers of the stomach and lung, 20 years later. (More on Time.com: Digital Diagnosis 2010: The Most Popular Health Stories of the Year)

Deaths from esophageal cancer were reduced by 60% in the aspirin-takers (who took the drug for at least five years), compared with the placebo group. Lung cancer deaths were reduced by 30%, colorectal cancer deaths were cut by 40% and prostate cancer deaths were lowered by 10%, compared with the patients who got placebo.

What’s more, the longer people took aspirin, the greater their reduction in cancer risk. The findings are in line with other research that has found anticancer benefits of aspirin in the lab, as well as observational studies that have shown aspirin’s protective effect against colorectal and other cancers. Researchers say the drug’s benefit may have to do with its anti-inflammatory effect.

But while the new study is compelling, cancer experts are not yet recommending that people start taking a daily aspirin for cancer prevention. And doctors warn against starting an aspirin regimen without first consulting a physician about side effects like stomach bleeding and hemorrhagic strokes. (More on Time.com: Could Painkiller Use in Pregnancy Cause Problems in Baby Boys?)

Still, Rothwell told NPR’s Shots blog that the anticancer effect of aspirin is “quite a lot bigger” than its protection against heart attacks and strokes. “So I think in the fullness of time, preventing cancer will be seen to be the main reason for taking aspirin in healthy individuals,” Rothwell said. NPR reports:

He started taking a daily dose of aspirin a couple of years ago as the results of his study emerged. “It was looking as though there was something going on, and I thought it was a sufficiently large benefit to be worth doing something about,” says the 46-year-old researcher.

Rothwell says the “sensible time” to start taking aspirin “would be before the risk of cancer starts to rise, at about 45.” He says prophylactic aspirin is “worth thinking about” for people with a family history of early cancers.

Study author Tom Meade, emeritus professor of epidemiology at the London School of Hygiene & Tropical Medicine, agrees. “These are very exciting and potentially important findings. They are likely to alter clinical and public health advice about low dose aspirin because the balance between benefit and bleeding has probably been altered towards using it,” he said in a statement.